Estimation of blood glucose in diabetes mellitus

Blood glucose  Blood glucose is normally maintained within a narrow range under various conditions insulin and glucagon, and other hormones as growth hormone and cortisol.  The most common disorder of carbohydrate metabolism is diabetes mellitus characterized by high blood glucose level  Measurement of blood glucose is one of the most commonly performed tests in clinical biochemistry labs of hospitals

Diabetes Mellitus: Common signs, symptoms and Lab results  Hyperglycemia  Polyuria and glucosuria  Polydipsia  Polyphagia

Laboratory tests for glucose  Fasting plasma glucose is measurement of plasma glucose after 8 hours of fasting (no caloric intake)  Normal level: mmol/l ( mg/dL).  OGTT (Oral Glucose tolerance Test) and 2-hour post-prandial test: Serial measurement of plasma glucose before and after a specific amount of glucose given orally (75g glucose) 

Impaired glucose tolerance When fasting plasma glucose or 2- hour postprandial glucose level is above normal but below diabetic level

Criteria for Diagnosis of DM* *American Diabetes Association (ADA), 2015

zHemoglobin A 1C (A1C) is produced due to non-enzymatic glycosylation of hemoglobin zIt is used to estimate glycemic control in the last 1-2 months zRecommended for the detection of type 2 DM zHBA 1C and fasting plasma glucose are effective in diagnosing diabetes zCut-off point of  6.5 % is used to diagnose diabetes HEMOGLOBIN A 1C

Comparison of type 1 and type 2 DM Type 1 DiabetesType 2 Diabetes Age of onsetUsually during childhood or puberty Frequently after age 35 Prevalence %10% of diagnosed diabetics 90% of diagnosed diabetics Defect or deficiencyβ cells are destroyed, eliminating insulin production Insulin resistance combined with inability of β cells to produce appropriate quantities of insulin KetoacidosisCommonrare Plasma InsulinLow to absentHigh early in disease; low in disease of long duration TreatmentInsulin is always necessary Diet, exercise, oral hypoglycemic drugs, +/- insulin

y Acetone (excreted by lungs, characteristic smell in diabetic ketoacidotic patients) y Acetoacetate y β-Hydroxybutyrate yProduced by the liver and utilized for energy production by peripheral tissues Ketone Bodies

Blood glucose Assay zBlood glucose is detected by a series of enzymatic reactions that ultimately form a colored product. z The intensity of color is proportional to the amount of glucose present in blood z Color intensity is determined spectrophotometerically by measuring the absorbance of the colored solution at a wavelength of 546nm

Procedure TestStandardBlank Reagent2.5 ml sample 25  l -- Standard- 25  l - H2OH2O- - Mix and incubate for 10 minutes at room temperature Measure absorbance at 546 nm

Calculation z Glucose conc (mmol/l) = Abs of sample Abs of standard X Conc of standard (5.6 mmol/l) Plasma Glucose: …………………………………………

Normal blood glucose range 3.9–5.6 mmol/L (70–100 mg/dL )

Urine analysis using dipstick: Principle:  Dipsticks are plastic strips impregnated with chemical reagents which react with specific substances in the urine to produce color-coded visual results  They provide quick determination of pH, protein, glucose and ketones. The depth of color produced is proportional to the conc. of the substance in urine  Color controls are provided against which the actual color produced by the urine sample can be compared

Procedure:  Dip the dipstick in the urine sample provided  Remove it immediately  Wipe off the excess urine  Read the color produced within 60 seconds  Compare color changes with the control charts provided

ItemObservationComment Protein Glucose Ketones pH Chemical Properties: